This invention relates in general to oil drainage and relates more particularly to an oil drainage coupler that facilitates fast safe drainage of crankcase oil from pans of vehicles such as cars and trucks. This coupler is particularly advantageous for use by vehicle maintenance facilities.
Many oil drainage plugs have been designed to facilitate crankcase oil drainage by the vehicle owner. Because these owners do not typically have access to a hydraulic lift, such changes are often inordinately difficult to perform and are especially difficult to perform without spilling oil. In general, the owner jacks up the vehicle, slides under the vehicle to remove the plug, quickly slides an oil receiver under the oil pan, drains the oil and then replaces the plug. Even if the car is raised on a typical car jack, this process is performed in a cramped space and is difficult to complete without spilling or splashing oil. Therefore, many of these drainage plugs are aimed at simplifying changing of the oil by vehicle owners.
In recent years a number of vehicle service outlets have been established that specialize in fast, inexpensive routine servicing of vehicles. These outlets typically change the crankcase oil, replace the oil filter, top off transmission and differential lubrication and, as needed, replace the air filter. Because of the high volume of customers serviced by these outlets, it is important to quickly drain and store crankcase oil. Such quick drainage and storage of oil would also be advantageous for vehicle repair and service facilities that do not specialize in this narrow line of service.
Some service facilities extract the dirty oil by inserting an oil extraction tube through the motor oil dipstick and then pumping oil out of the crankcase. This procedure is simple, quick and avoids the below-indicated risks of liability, but it drains only about 85% of the oil in the crankcase, leaving behind some of the dirtiest oil located in the bottom of the oil pan.
More typically, crankcase oil is drained by elevating a vehicle on a hydraulic lift, rolling an oil drum underneath the oil pan of the vehicle, removing a drainage plug from the oil pan and allowing the oil to flow out of the oil pan into the oil drum. Typically, in a hole in the top of the oil drum is a large funnel that can be elevated to a height just below the oil pan. This ensures that substantially all of the drained oil winds up in the oil drum and this funnel. The drainage plug is then screwed back into the oil pan and several quarts of oil are poured into the top of the crankcase.
Unfortunately, this procedure is relatively slow and involves a small, but expensive risk to the service facility. If the plug is excessively tighten into the oil pan, then threads in the oil pan can be stripped, thereby exposing the facility to the cost of replacing the oil pan. Even if the service personnel of the facility are skilled and conscientious, these threads could have been damaged in a previous oil change so that proper replacement of the oil pan drainage plug could still strip these threads.
If the oil pan drainage plug is insufficiently tightened, vibration from normal operation of the vehicle can cause the drainage plug to unscrew, thereby enabling the oil to drain out of the crankcase. If this occurs, then there is a significant likelihood of major engine damage. The liability for such a repair is many times the profit made on such service and therefore is a very real risk for such vehicle service facilities. In addition, an unscrupulous customer wanting free major engine repair could intentionally remove the drainage plug and claim that the service facility is responsible. It would therefore be advantageous to have an oil drainage plug that enables oil drainage without unscrewing the oil drainage plug.
It would be advantageous for the plug to be capable of coupling to a fitting on the end of a hose to enable the oil to be drained through the hose into a remote oil receptacle, thereby avoiding the need to roll an oil drum beneath the vehicle. The plug and fitting should connect by means of a quick coupler so that the hose can be simply and quickly coupled and decoupled from the plug. This coupling should be vacuum-tight so that a vacuum-enhanced drainage of oil can be utilized. The plug should fit into the oil pan such that the oil drains through a hole that is substantially flush with the bottom of the oil pan so that substantially all of the oil can be drained from the oil pan. The plug should not extend substantially below the oil pan so that it is not susceptible to breaking off by collision with an obstacle in the roadway. The plug should contain a valve located above the bottom of the oil pan so that if the part of the plug external to the oil pan is broken off, the valve will still keep oil from draining from the oil pan. The coupling should also be simple and rugged to reduce the cost and increase the durability and dependability of the coupling.
The following 6 patents present plugs that do not need to be removed to drain oil from the oil pan, but each lacks at least one of the above-indicated desirable traits for a drainage coupler. In U.S. Pat. No. 4,086,981, the plug is not adapted to couple to any type of fitting, let alone to a vacuum tight, quick coupler type fitting. This plug extends a substantial distance below the oil pan, thereby being subject to damage by road obstacles. The valve portion of this plug is outside of the oil pan so that, if this plug breaks off, oil will drain out of the oil pan. This plug not only has a complex structure, but also requires an expensive procedure to retrofit this plug into existing vehicles.
In U.S. Pat. No. 3,743,053, the plug is coupled to a pump mounted on the vehicle motor to pump oil from the oil pan. This pump adds substantial cost to the system and a retrofit with this plug is complicated and expensive. The plug extends substantially outside of the oil pan and the valve is located partially below the bottom of the oil pan so that if this plug breaks off then oil will drain out of the oil pan. This plug is not adapted to couple to a standard oil drainage system in a service facility so that it is not suitable for use by quick service facilities.
In U.S. Pat. No. 3,967,697, the plug is adapted to couple to a small oil receptacle for oil drainage by the vehicle owner. It is not adapted to couple to a vacuum oil drainage system. Because the drain plug is not removed during oil drainage, the risk of cross-threading the drain plug into the oil drain is eliminated, but this plug is still subject to the risk of over or under tightening the plug after oil drainage. The plug also includes a gasket that can degrade during vehicle operation, producing the risk of eventual leakage past this gasket.
In U.S. Pat. Nos. 4,269,237 and related case 4,373,561, the plug is adapted for drainage by the vehicle owner into a special collecting device. The valve is opened by a spigot of outside diameter substantially equal to the inside diameter of a bore in the oil plug. Therefore, different diameter plugs cannot couple to a single fitting or else all plugs have the same diameter opening which is determined by the smallest diameter plug, thereby limiting the rate of oil drainage. Also, no vacuum tight seal is produced to the spigot. The drainage plug also contains a pair of seals that can not only dry out during vehicle use, but can also be damaged by the spigot that is inserted into the plug to open the oil valve, thereby enabling oil to leak past the valve during normal vehicle operation. The drainage opening in the plug is above the bottom of the oil pan so that the dirtiest oil will not be drained from the oil pan.
In U.S. Pat. No. 4,756,349, no vacuum connection is produced to an associated fitting and the plug extends significantly below the bottom of the oil pan. The valve is opened by a tube of outside diameter substantially equal to the inside diameter of a bore in the oil plug. Therefore, different diameter plugs cannot couple to a single fitting or else all plugs have the same diameter opening which is determined by the smallest diameter plug, thereby limiting the rate of oil drainage. The valve is in the portion of the plug that extends outside of the oil pan and therefore, if this portion in broken off, the oil will drain out of the oil pan.
In U.S. Pat. No. 4,776,430, a drain pipe, connected to a vacuum system, is screwed into the oil plug to remove oil. Thus, threads can be stripped during an oil change and no ability to quick couple a vacuum system to the oil pan is presented. An L-shaped tube extending below the oil pan is at risk to breakage during normal vehicle operation. A rubber seal in the plug can dry out as it ages and allow oil leakage past the valve.
In U.S. Pat. No. 3,720,287, an assembly is screwed into the oil plug to enable a valve in the plug to be opened. These threads can be stripped during oil drainage and no ability to quick couple is provided. Oil drains through holes significantly above the bottom of the oil pan so that the dirtiest oil cannot be drained from the oil pan.
In U.S. Pat. No. 4,745,894, a drainage coupling is provided that can be quickly coupled. However, this coupling is relatively complicated and expensive. In addition, a portion of the valve extends outside of the oil pan so that if this portion is broken off, then oil will drain from the oil pan. Also, the valve includes a cylindrical section that must be pushed up by a mating cylinder in the fitting. Therefore, either each plug size must have an associated sized fitting or else the drain opening of all sizes is limited to the size of the opening in the smallest diameter plug.
In U.S. Pat. No. 4,530,421, the plug extends a significant distance outside of the oil pan and therefore is subject to breakage during vehicle use. The valve is contained in this section so that oil will drain from the oil pan if this section breaks off. The valve is opened by a tube of diameter substantially equal to the diameter of the opening in the plug so that either each plug has an associated sized fitting or the opening diameter is limited to the diameter of the smallest plug. The plug includes a seal that can begin to leak as it ages. No vacuum tight seal is produced to enable a vacuum enahanced rate of drainage.